The important parameter determining the superlens resolution is the wave vector \(k_0\)  and its \(x\)  component \(k_x\) . Specifically, to achieve subwavelength resolution, the superlens needs to transmit high spatial frequency components with \(k_x>k_0\) . In such a case, the \(y\)  component of the wave vector \(k_y = \sqrt{k_0^2 - k_x^2}\)  is imaginary and thus it describes evanescent waves. The key characteristic of the superlens is the capability to amplify these rapidly decaying evanescent waves [1]}.
